In recent years prevention of disease to animal husbandry barns has reached the extent where attempts are made to ensure that all air entering the barn is filtered of pathogens that can be airborne. For this reason a number of companies provide systems for filtering the air at the intakes. Typically the air intakes communicate with the roof space with the air entering into the containment area through the ceiling and also from the wall. This can be done by providing filtration membranes engaging the air as it enters the roof space or it can be done by providing on each intake duct a separate membrane assembly attached onto the intake opening within the roof space.
Much work has been done, for example by Noveko of Quebec, on developing improved membranes which provide an effective and cost efficient filtration system. However it is known that pathogens can still enter the containment area by the fans louvers and disease can still strike, often with very damaging results.
However it is known that pathogens can still enter the containment area through closed fans louvers, due to known negative air pressure (0.05 to 0.2 inch of water) inside the building. It has been experimented that a 24″ fan that is not running even with the louvers closed, can allow in as much as 400 cfm of viral contaminated air into the building (with inside static pressure of 0.05 inch of water), and that 3×24″ fans can allow in as much viral contaminated air into a building as a 12″ running fan would do if it were used to push viral contaminated air into a building, which may cause airborne pathogen to strike, often with very damaging results.
The animals concerned are typically pigs and poultry but of course other animals require the same protection from pathogens that can be airborne.
The arrangement described herein is applicable not only to the sector of animal confinement barns, but also to any other sectors where ventilation applies, such as industry, commercial, residential applications, or any other, where backdraft must be controlled for whatever reason.